The subject invention relates to sheet transporting methods and apparatus, sheet feeder systems, and methods and apparatus for transporting documents, papers, sheet-like material and sheets from a stack.
There has been an increasing demand for sheet transporting methods and apparatus, sheet feeder systems, and methods and apparatus for transporting documents, papers, sheet-like material and other sheets from a stack, rapidly and reliably without paper jams and other disturbances.
To a large extent, this demand has been sparked by the desire of public utilities, banks and other institutions to economize, automate and speed up the processing of payments by customers. In practice, the resulting advanced remittance processing systems require high-speed stackers and unstackers or sheet feeders capable of handling such items as bank checks and remittance stubs of various intermixed lengths, thicknesses, formats, textures and surface finishes. Such sheet feeding systems are to be capable of feeding or unstacking received documents or sheets in their original sequential order in which they were fed into the stacking apparatus or stack from which the documents or sheets are to be fed.
To avoid jams, document or account mixup and other disagreeable disturbances, it is most important that the documents or sheets be clearly, reliably and rapidly separated from each other during any unstacking process.
In this respect, the utility of the subject invention is not limited to remittance processing, or to any other field herein particularly emphasized, but may extend to microfilm or microfiche systems or to a great variety of other sheet stacking and unstacking processes and equipment.
By way of example, reference may be had to U.S. Pat. No. 4,303,234, by Dale Plum, issued Dec. 1, 1981 for Deskewing Document Feed Tray, to the common assignee hereof.
The system disclosed in that patent feeds a plurality of documents in a document transport system under the force of gravity toward a document pickup and curls each document slightly as it approaches the pickup, so as to give the document a force element pushing a portion thereof against the pickup. The lowermost corner of a skewed curled document is pressed against a stationary surface to square it against such surface, thereby reducing any skewing relative thereto. The squared document is delivered into the nip of a pair of pickup rollers.
In practice, one of the pickup rollers, such as the lower roller, may be spring-loaded into direct contact with the other or upper roller, when no documents are being fed into the unit. The lower roller is then driven at a reverse torque to the upper roller, but the upper roller overcomes such reverse torque, causing the lower roller to turn in the forward direction as long as it is in direct or indirect driving engagement with the top roller.
When multiple documents are fed to the nip between the rollers, the upper roller pulls only the top document into the transport, while the lower roller enganges the next lower document, rejecting it by action of the reverse torque at which the lower roller is driven through a slip clutch.
The objective thus is to drive only one document at the time into or through the transport.